'Affordable' Housing in National Parks?

It has been argued that more affordable (which often means 'cheap') homes need to be built in National Parks in the UK to avoid young people and workers in those parks being priced out of the market (https://www.theguardian.com/environment/2020/jan/29/more-affordable-housing-should-be-built-in-national-parks). It is clearly the case that many of the parks attract people who can pay for expensive second homes (in some cases rarely used) and that house builders sometimes sit on building land to maximise their profits. I do fear, however, that the construction of 'affordable' homes might change the nature of the parks themselves (it's not much of a park, if it's built on). It would also be difficult to control the resale of such properties (they might well become second homes?). I appreciate that many people like to own their house but would it not be a better to encourage the parks authorities to build housing, with the very highest environmental specifications, for rental to young folk or their own workers? This would solve the problem of enabling people to remain in the area whilst also controlling the problems of resale and environmental issues.